When someone (from Internet or my private lan) request a page to my public ip 11.11.11.11 on port 80, my webserver respond to it correctly. But when i want to check access.log of my web server i can see only my Zyxel router ip 192.168.1.1 logged.

I suppose there is a NAT problem, it seems that the Zyxel subsitutes its ip address as SRC of IP packets coming to my webserver.

What i have to do to get a properly logged web requests with public clients ip addresses?
Router is the Zyxel USG 100